rustdoc: fix corner case in search keyboard commands

src/librustdoc/html/static/js/search.js

@@ -1491,6 +1491,7 @@ function initSearch(rawSearchIndex) {
         const target = searchState.focusedByTab[searchState.currentTab] ||
             document.querySelectorAll(".search-results.active a").item(0) ||
             document.querySelectorAll("#titles > button").item(searchState.currentTab);
+        searchState.focusedByTab[searchState.currentTab] = null;
         if (target) {
             target.focus();
         }

src/test/rustdoc-gui/search-keyboard.goml

@@ -0,0 +1,28 @@
+// Checks that the search tab results work correctly with function signature syntax
+// First, try a search-by-name
+goto: "file://" + |DOC_PATH| + "/test_docs/index.html"
+write: (".search-input", "Foo")
+// To be SURE that the search will be run.
+press-key: 'Enter'
+// Waiting for the search results to appear...
+wait-for: "#titles"
+
+// Now use the keyboard commands to switch to the third result.
+press-key: "ArrowDown"
+press-key: "ArrowDown"
+press-key: "ArrowDown"
+assert: ".search-results.active > a:focus:nth-of-type(3)"
+
+// Now switch to the second tab, then back to the first one, then arrow back up.
+press-key: "ArrowRight"
+assert: ".search-results.active:nth-of-type(2) > a:focus:nth-of-type(1)"
+press-key: "ArrowLeft"
+assert: ".search-results.active:nth-of-type(1) > a:focus:nth-of-type(3)"
+press-key: "ArrowUp"
+assert: ".search-results.active > a:focus:nth-of-type(2)"
+press-key: "ArrowUp"
+assert: ".search-results.active > a:focus:nth-of-type(1)"
+press-key: "ArrowUp"
+assert: ".search-input:focus"
+press-key: "ArrowDown"
+assert: ".search-results.active > a:focus:nth-of-type(1)"